1. Field of the Invention
The present invention relates to radio telecommunication devices with a feature for displaying received messages, such as a pager receiver, a mobile telephone or a cordless telephone.
2. Description of the Related Art
As a new type of a paging system, a system has recently been developed in which a base station transmits message information, and one of the pager receivers subscribed to this system displays the message information. A paging signal used in this system is formed as follows. That is, one frame is time-divided into a plurality of groups each of which is time-divided into a synchronization word and a plurality of calling words. In each calling word are inserted an identification (ID) code and a message code.
When calling a pager receiver, a caller dials a telephone numbers assigned to the pager receiver, thus reaching the base station and transmits message information to the base station. Then the base station generates the ID code assigned to the selected pager receiver and the message code corresponding to the message information. The ID code and the massage code are inserted into one of an empty calling words in a group to which that pager receiver belongs among a plurality of groups in one frame and transmitted to the pager receiver.
On the other hand, the pager receiver is arranged as follows. That is, the paging signal transmitted from the base station is received by a radio circuit through an antenna and demodulated by a demodulation circuit for subsequent application to a control circuit. The control circuit checks the I code contained in the demodulated paging signal with the self-ID code previously stored an ID-ROM. When a coincidence occurs between the codes, the control circuit recognizes the generation of a call to the self-receiver to produce a ringing signal which is applied to a loudspeaker via a driving circuit. A ringing tone is emanated from the loudspeaker, whereby the user is informed that a call has been made to him.
Upon the occurrence of a coincidence between the ID codes, the control circuit enters the message code received following the ID code. After being subjected to an error correcting process, the message code is decoded and the decoded message data is applied to a display driving circuit. Consequently the message is displayed on a liquid crystal display (LCD) by the display driving circuit. Therefore, the user can understand the message from the caller through the liquid crystal display at the time of generation of the call. The display message is erased from the liquid crystal display when the user depresses a stop switch.
The message code is displayed on the liquid crystal display and transferred from the control circuit to a message memory to be stored therein. The message memory consists of a random access memory (RAM) which has areas required to store a plurality of message codes. When the user depresses a display switch with message codes stored in the message memory, a message code is read from the message memory by the control circuit. The read message code is decoded by the control circuit and then applied to the display driving circuit so that it is displayed on the liquid crystal display. Even after the display of a message on the liquid crystal display has been erased, therefore, the user can read the message from the message memory to watch it on the display by depressing the display switch.
However, such a conventional receiver only has a received message displaying feature in which only one message code is read from the message memory and displayed on the display each time the display switch is depressed once. Where many message codes are stored in the message memory, therefore, the display switch might have to be operated many times so as to display a desired message code, causing trouble to display operations.